absit_omen
Well-Known Member
Anybody any first hand experience of using the New Zealand manufactured Anchor Buddy (CAB 30 all chain model)?
Anchor Buddy
- Thread starter absit_omen
- Start date
hylass
Well-Known Member
You have a very interesting web page: http://alain.fraysse.free.fr
wich give all explanation on "anchor Buddy" (or chum or Angel) and how to use them, where to place them on the mooring line and what advantage they give.. with all mathematical formulas..
wich give all explanation on "anchor Buddy" (or chum or Angel) and how to use them, where to place them on the mooring line and what advantage they give.. with all mathematical formulas..
hylass
Well-Known Member
see: [url]http://alain.fraysse.free.fr/sail/rode/static/static.htm[/url]
2. Kellet
In the previous page, formula (1.2) gave the critical value Fc that lifts an homogeneous rode completely:
(1.2)
If we add a weight K at distance Lk from the bow (fig. 1.6), what improvement can we expect beyond Fc?
Figure 1.6 - Kellet
The equations of this problem are discussed in the static theory chapter. There is no simple expression of the result, but if we assume the scope is greater than 3:1, an acceptable approximation (with less than 6% error) is given by:
(1.6)
These expressions show the improvement equals the kellet weight K multiplied by the ratio Lk/H. Consequently, the best improvement is obtained by putting the kellet near the anchor, where it equals the kellet weight K multiplied by the scope N.
With the same kellet in the middle of the rode, the improvement would be halved.
An all-textile rode with a kellet close to the anchor has the same performance as an all-chain rode of same length, with only half the total rode weight. This confirms that concentrating the weight down the rode, if possible, would be much more effective than spreading it along the rode.
Unfortunately, handling capabilities limit the weight of actual kellets around 22 kg (50 lb), which is insufficient in severe wind conditions unless the scope is very large.
In addition, using a kellet does not significantly improve the swinging radius R.
2. Kellet
In the previous page, formula (1.2) gave the critical value Fc that lifts an homogeneous rode completely:
(1.2)
If we add a weight K at distance Lk from the bow (fig. 1.6), what improvement can we expect beyond Fc?
Figure 1.6 - Kellet
The equations of this problem are discussed in the static theory chapter. There is no simple expression of the result, but if we assume the scope is greater than 3:1, an acceptable approximation (with less than 6% error) is given by:
(1.6)
These expressions show the improvement equals the kellet weight K multiplied by the ratio Lk/H. Consequently, the best improvement is obtained by putting the kellet near the anchor, where it equals the kellet weight K multiplied by the scope N.
With the same kellet in the middle of the rode, the improvement would be halved.
An all-textile rode with a kellet close to the anchor has the same performance as an all-chain rode of same length, with only half the total rode weight. This confirms that concentrating the weight down the rode, if possible, would be much more effective than spreading it along the rode.
Unfortunately, handling capabilities limit the weight of actual kellets around 22 kg (50 lb), which is insufficient in severe wind conditions unless the scope is very large.
In addition, using a kellet does not significantly improve the swinging radius R.
absit_omen
Well-Known Member
Re: see: [url]http://alain.fraysse.free.fr/sail/rode/static/static.htm[/url]
Hylas, Many thanks. I think I shall just save up for a Spade Anchor!!
Hylas, Many thanks. I think I shall just save up for a Spade Anchor!!
Sea Devil
Well-Known Member
Re: see: [url]http://alain.fraysse.free.fr/sail/rode/static/static.htm[/url]
I have used a New Zealand anchor chum and before that a DIY version and consider them excellent. There is no doubt that in dodgy conditions - big swell coming into the anchorage - they greatly increase the holding power of the anchor. Instead of the problems of laying a 2nd anchor when things get interesting it is much easier to lower a 'chum' device down the chain and has almost the same effect.
I have used a New Zealand anchor chum and before that a DIY version and consider them excellent. There is no doubt that in dodgy conditions - big swell coming into the anchorage - they greatly increase the holding power of the anchor. Instead of the problems of laying a 2nd anchor when things get interesting it is much easier to lower a 'chum' device down the chain and has almost the same effect.
A
Anonymous
Guest
Re: see: [url]http://alain.fraysse.free.fr/sail/rode/static/static.htm[/url]
[ QUOTE ]
they greatly increase the holding power of the anchor.
[/ QUOTE ]Without any detailed maths, it is quite easy to see why this should be so in practice. Anchors don't readily drag or come out if the pull is horizontal. A chum brings more chain closer to the bottom and the catenary from the chum to the anchor will be more horizontal than it would otherwise have been.
[ QUOTE ]
they greatly increase the holding power of the anchor.
[/ QUOTE ]Without any detailed maths, it is quite easy to see why this should be so in practice. Anchors don't readily drag or come out if the pull is horizontal. A chum brings more chain closer to the bottom and the catenary from the chum to the anchor will be more horizontal than it would otherwise have been.
hylass
Well-Known Member
Re: see: [url]http://alain.fraysse.free.fr/sail/rode/static/static.htm[/url]
--------------------------------------------------------------------------------
"CHUM" they only marginaly increase the holding power of the anchor.
--------------------------------------------------------------------------------
"Without any detailed maths, it is quite easy to see why this should be so in practice. Anchors don't readily drag or come out if the pull is horizontal. A chum brings more chain closer to the bottom and the catenary from the chum to the anchor will be more horizontal than it would otherwise have been."
YES, theoriticaly you are absolutely right... and praticaly too.. for moderate winds.. but unless you can use a very heavy Kellet, in strong winds, (when anchoring is realy a problem..) the action of the kellet is only marginal..
"I have used a New Zealand anchor chum and before that a DIY version and consider them excellent. There is no doubt that in dodgy conditions - big swell coming into the anchorage - they greatly increase the holding power of the anchor. Instead of the problems of laying a 2nd anchor when things get interesting it is much easier to lower a 'chum' device down the chain and has almost the same effect. "
This is also a very old wisdom.. and in dodgy conditions - big swell coming into the anchorage... the improvment is mostly psychological..
As Alain FRAYSSE says in his very well documented study: - "Unfortunately, handling capabilities limit the weight of actual kellets around 22 kg (50 lb), which is insufficient in severe wind conditions unless the scope is very large.
In addition, using a kellet does not significantly improve the swinging radius R. "
And using detailed maths, it is quite easy to see why this should be so in practice: with strong winds, the pulling force on the mooring chain can reach more that 1 or 2 tons.. The action of a "kellet" of around 20 kg is only marginal in relation with the pulling force..
If the use of a kellet will help you to sleep well in an anchorage.. Please use it.. but personnaly, I will never trust a product that I consider as a "Gadget"..
--------------------------------------------------------------------------------
"CHUM" they only marginaly increase the holding power of the anchor.
--------------------------------------------------------------------------------
"Without any detailed maths, it is quite easy to see why this should be so in practice. Anchors don't readily drag or come out if the pull is horizontal. A chum brings more chain closer to the bottom and the catenary from the chum to the anchor will be more horizontal than it would otherwise have been."
YES, theoriticaly you are absolutely right... and praticaly too.. for moderate winds.. but unless you can use a very heavy Kellet, in strong winds, (when anchoring is realy a problem..) the action of the kellet is only marginal..
"I have used a New Zealand anchor chum and before that a DIY version and consider them excellent. There is no doubt that in dodgy conditions - big swell coming into the anchorage - they greatly increase the holding power of the anchor. Instead of the problems of laying a 2nd anchor when things get interesting it is much easier to lower a 'chum' device down the chain and has almost the same effect. "
This is also a very old wisdom.. and in dodgy conditions - big swell coming into the anchorage... the improvment is mostly psychological..
As Alain FRAYSSE says in his very well documented study: - "Unfortunately, handling capabilities limit the weight of actual kellets around 22 kg (50 lb), which is insufficient in severe wind conditions unless the scope is very large.
In addition, using a kellet does not significantly improve the swinging radius R. "
And using detailed maths, it is quite easy to see why this should be so in practice: with strong winds, the pulling force on the mooring chain can reach more that 1 or 2 tons.. The action of a "kellet" of around 20 kg is only marginal in relation with the pulling force..
If the use of a kellet will help you to sleep well in an anchorage.. Please use it.. but personnaly, I will never trust a product that I consider as a "Gadget"..
A
Anonymous
Guest
Maths and anchoring
You have misquoted me by juxtaposition - though I am sure that it wasn't intentional. I would like to set the record straight.
I believe the maths in the study you quote is faulty. I base that on the fact that it is predicting different behaviour to that experienced by people who have anchored as a way of life on a long-term basis, and it also seems to be at variance with Earl Hinz's observations.
The maths associated with the forces, masses and lengths is all pretty straightforward but the conclusions all depend on the mathematical model of the anchor on an actual sea bed and that is maybe where the problem lies.
You said "...with strong winds, the pulling force on the mooring chain can reach more that 1 or 2 tons."
I'm actually researching this at the moment for my own boat. I have found that 10mm anchor chain is only rated for one tonne working load and a Plastimo 14mm galvanised shackle (considerably larger than most yachtsmen fit to a 10mm chain to secure the anchor) has a max safe working load of only 700kg. Purpose galvanised anchor connectors (non-swivel) have a safe working load of 1250kg - which is more appropriate than a shackle. Anyway, the suggestion that the force on a mooring chain of a yacht would be one or two tonnes seems wrong - if that were true then we'd all be sharing stories of broken anchor chain, shackles, bent anchors - not to mention cleats, samson posts or windlass mountings. I believe that Earl Hinz published measured figures - I am going to the Cruising Association library next week and will have a look.
You have misquoted me by juxtaposition - though I am sure that it wasn't intentional. I would like to set the record straight.
I believe the maths in the study you quote is faulty. I base that on the fact that it is predicting different behaviour to that experienced by people who have anchored as a way of life on a long-term basis, and it also seems to be at variance with Earl Hinz's observations.
The maths associated with the forces, masses and lengths is all pretty straightforward but the conclusions all depend on the mathematical model of the anchor on an actual sea bed and that is maybe where the problem lies.
You said "...with strong winds, the pulling force on the mooring chain can reach more that 1 or 2 tons."
I'm actually researching this at the moment for my own boat. I have found that 10mm anchor chain is only rated for one tonne working load and a Plastimo 14mm galvanised shackle (considerably larger than most yachtsmen fit to a 10mm chain to secure the anchor) has a max safe working load of only 700kg. Purpose galvanised anchor connectors (non-swivel) have a safe working load of 1250kg - which is more appropriate than a shackle. Anyway, the suggestion that the force on a mooring chain of a yacht would be one or two tonnes seems wrong - if that were true then we'd all be sharing stories of broken anchor chain, shackles, bent anchors - not to mention cleats, samson posts or windlass mountings. I believe that Earl Hinz published measured figures - I am going to the Cruising Association library next week and will have a look.
hylass
Well-Known Member
Re: Maths and anchoring
Dear Lemain,
I have also anchored as a way of life since 13 years now.. But I don't know if it is enough to be considered as a long-term basis?? :0)..
A 10 mm chain is suggested for boats between 10,50 and 12,50 metres LOA. (French legislation).
The force exerted by a Force 9 wind (45 knots) on a 10,50 m boat is around 820 daN and for a 12,50 m boat : 1100 daN… But this is only static load, if there is some surge or waves, this force can easily be multiplied by 2 – 3 – 4…(During short peaks of load) and this is why it is so important to use a nylon spring line to give elasticity to the mooring rode (see all explanation and mathematic study on "Alain Fraysse's Web Page)
On his book, "The complete book of mooring and anchoring" ( 2001 Edition) page 19 Table 2-2, Earl Hinz give an example of load calculated by ABYC method:- For a 37ft 9 in boat, (approx. 12 meters) and 42 knot of wind, the load on the storm anchor is 2120 lbs (more than one ton). and these forces don't have any relation with either the type of anchor used or the type of sea bed.. They are related with the speed of the wind and the surface area of the boat.. the anchor and the sea bed should only be capable to resist this load..
A 10 mm chain of good quality has a breaking load of 5,000 daN and yes, a working load of 1500 daN… and this is again why it is so important to use a snubber to absorb the peak of load generated by surge.. A 18 mm Nylon Rope as a breaking load of 6500 daN and a working load of 1600 daN –
A good 12 mm stainless steel shackle (see for example Wichard) has a breaking and working load, similar to those of the 10 mm chain. On my own boat, I don't use a shackle or a weak anchor connector, (breaking load much lower than the 10 mm chain) but a 12 mm toogle (the same used for the rigging – see next issue of PBO).
I can assure you that along the long term cruisers community, stories of broken anchor chain, shackles, bent anchors - not to mention cleats… are not an exception..
And with such high loads, the effect of a 20 kg Chum is just peanuts…
Dear Lemain,
I have also anchored as a way of life since 13 years now.. But I don't know if it is enough to be considered as a long-term basis?? :0)..
A 10 mm chain is suggested for boats between 10,50 and 12,50 metres LOA. (French legislation).
The force exerted by a Force 9 wind (45 knots) on a 10,50 m boat is around 820 daN and for a 12,50 m boat : 1100 daN… But this is only static load, if there is some surge or waves, this force can easily be multiplied by 2 – 3 – 4…(During short peaks of load) and this is why it is so important to use a nylon spring line to give elasticity to the mooring rode (see all explanation and mathematic study on "Alain Fraysse's Web Page)
On his book, "The complete book of mooring and anchoring" ( 2001 Edition) page 19 Table 2-2, Earl Hinz give an example of load calculated by ABYC method:- For a 37ft 9 in boat, (approx. 12 meters) and 42 knot of wind, the load on the storm anchor is 2120 lbs (more than one ton). and these forces don't have any relation with either the type of anchor used or the type of sea bed.. They are related with the speed of the wind and the surface area of the boat.. the anchor and the sea bed should only be capable to resist this load..
A 10 mm chain of good quality has a breaking load of 5,000 daN and yes, a working load of 1500 daN… and this is again why it is so important to use a snubber to absorb the peak of load generated by surge.. A 18 mm Nylon Rope as a breaking load of 6500 daN and a working load of 1600 daN –
A good 12 mm stainless steel shackle (see for example Wichard) has a breaking and working load, similar to those of the 10 mm chain. On my own boat, I don't use a shackle or a weak anchor connector, (breaking load much lower than the 10 mm chain) but a 12 mm toogle (the same used for the rigging – see next issue of PBO).
I can assure you that along the long term cruisers community, stories of broken anchor chain, shackles, bent anchors - not to mention cleats… are not an exception..
And with such high loads, the effect of a 20 kg Chum is just peanuts…
Sea Devil
Well-Known Member
never trust a product that I consider as a \"Gadget\"..
I take anchoring very very seriously - my last boat 36ft = 11m had a main anchor of CQR 45lbs and 10mm chain - The Chum/Kellet/ has been around for decades and will certainly help. to quote a previous post:-
A chum brings more chain closer to the bottom and the catenary from the chum to the anchor will be more horizontal than it would otherwise have been
This is not a gadget - I have seen 10mm chain bounce out of the water with 25 mtrs of the stuff out in 8mts depth - with the chum lowered down it it stopped breaking surface - it helped...
Vital to have laid the anchor properly and really dug it in - after that important to keep the cantanary down low as possible. Not really higher maths more common sense............. ducking!!!!
I take anchoring very very seriously - my last boat 36ft = 11m had a main anchor of CQR 45lbs and 10mm chain - The Chum/Kellet/ has been around for decades and will certainly help. to quote a previous post:-
A chum brings more chain closer to the bottom and the catenary from the chum to the anchor will be more horizontal than it would otherwise have been
This is not a gadget - I have seen 10mm chain bounce out of the water with 25 mtrs of the stuff out in 8mts depth - with the chum lowered down it it stopped breaking surface - it helped...
Vital to have laid the anchor properly and really dug it in - after that important to keep the cantanary down low as possible. Not really higher maths more common sense............. ducking!!!!
A
Anonymous
Guest
Re: Maths and anchoring
In case anyone following this thread isn't familiar with the non-SI unit daN, it is, in effect, 1kg.
[ QUOTE ]
On his book, "The complete book of mooring and anchoring" ( 2001 Edition) page 19 Table 2-2, Earl Hinz give an example of load calculated by ABYC method:- For a 37ft 9 in boat, (approx. 12 meters) and 42 knot of wind, the load on the storm anchor is 2120 lbs (more than one ton)
[/ QUOTE ]No, 2120 lbs is 962kg, i.e. 0.96 tonne.
[ QUOTE ]
A good 12 mm stainless steel shackle (see for example Wichard) has a breaking and working load, similar to those of the 10 mm chain.
[/ QUOTE ] I'm not sure that mixing stainless with galvanised chain is a good idea, particularly for long-term anchoring, due to potential electrolytic action.
[ QUOTE ]
On my own boat, I don't use a shackle or a weak anchor connector, (breaking load much lower than the 10 mm chain) but a 12 mm toogle (the same used for the rigging – see next issue of PBO).
[/ QUOTE ]Again, I'm not sure that using stainless is a good idea but I am not a metallurgist. My new Plastimo galvanised connector has a safe working load of 3000kg (i.e. 3 tonnes), it fits the Bruce anchor and the 10mm chain perfectly, rides nicely over the bow roller and looks seamanlike. I'm not sure that the same could be said of a toogle.
[ QUOTE ]
And with such high loads, the effect of a 20 kg Chum is just peanuts…
[/ QUOTE ]You are missing the point, I think. In the right direction, that 20 kg force is enough to pull the anchor free and lift it from the bottom (if it is less than 20kg, anyway). Applied in the right direction, 20kg force is not "peanuts".
In any case, to put my comment back into the context in which it was made, I was replying to ex-Bambola who said "There is no doubt that in dodgy conditions - big swell coming into the anchorage - they greatly increase the holding power of the anchor." If you look back to where I came in, we were not talking about anchoring in a force 9.
In case anyone following this thread isn't familiar with the non-SI unit daN, it is, in effect, 1kg.
[ QUOTE ]
On his book, "The complete book of mooring and anchoring" ( 2001 Edition) page 19 Table 2-2, Earl Hinz give an example of load calculated by ABYC method:- For a 37ft 9 in boat, (approx. 12 meters) and 42 knot of wind, the load on the storm anchor is 2120 lbs (more than one ton)
[/ QUOTE ]No, 2120 lbs is 962kg, i.e. 0.96 tonne.
[ QUOTE ]
A good 12 mm stainless steel shackle (see for example Wichard) has a breaking and working load, similar to those of the 10 mm chain.
[/ QUOTE ] I'm not sure that mixing stainless with galvanised chain is a good idea, particularly for long-term anchoring, due to potential electrolytic action.
[ QUOTE ]
On my own boat, I don't use a shackle or a weak anchor connector, (breaking load much lower than the 10 mm chain) but a 12 mm toogle (the same used for the rigging – see next issue of PBO).
[/ QUOTE ]Again, I'm not sure that using stainless is a good idea but I am not a metallurgist. My new Plastimo galvanised connector has a safe working load of 3000kg (i.e. 3 tonnes), it fits the Bruce anchor and the 10mm chain perfectly, rides nicely over the bow roller and looks seamanlike. I'm not sure that the same could be said of a toogle.
[ QUOTE ]
And with such high loads, the effect of a 20 kg Chum is just peanuts…
[/ QUOTE ]You are missing the point, I think. In the right direction, that 20 kg force is enough to pull the anchor free and lift it from the bottom (if it is less than 20kg, anyway). Applied in the right direction, 20kg force is not "peanuts".
In any case, to put my comment back into the context in which it was made, I was replying to ex-Bambola who said "There is no doubt that in dodgy conditions - big swell coming into the anchorage - they greatly increase the holding power of the anchor." If you look back to where I came in, we were not talking about anchoring in a force 9.
hylass
Well-Known Member
Re: Maths and anchoring
Dear Michael and Lemain
I will stop answering your posts as I know that they are people that I will never convince..
Sorry, but we are not playing on the same ground.. You are both using "common beliefs" and what you call "common sense"… I'm using mathematical formulas and I know that you will never trust mathematical demonstrations..
You trust "Kellets" and it helps you to sleep more deeply?? Then, please, use "Kellets" and use two or three of them if you want.. and have a good night.. I don't care, this is not my boat which is attached to your anchoring gear..
On my side, I'm living full time on my boat, she is all my belongings and believe me, I will never trust a kellet..
Michael:
" The Chum/Kellet/ has been around for decades"
Yes, this is absolutely true in UK, but either in the States or in France, very few people are using them..
The "Byblos" anchor has also been used for Centuries, and it is still used in some parts of the world, but it doesn't mean that it is a good anchor (Byblos anchor: Phoenician anchor made of a flat stone with a hole for the rope)
"A chum brings more chain closer to the bottom and the catenary from the chum to the anchor will be more horizontal than it would otherwise have been"
Again I'm sorry but I have to disagree with you.. If you perform mathematical simulations with the Chum at different places on the mooring chain, you will find that the place where the Chum is the most efficient to increase the holding, is as close as possible to the shank of the anchor. In this position, the Chum will keep the shank of the anchor more horizontal, but will not change (or very few increase) the angle of the chain.
As I said before, this is true with light or moderate winds, where nobody care about the holding of the anchor. but with strong winds, when some more holding will be appreciated, the weight of the chum is much too small to make a SENSIBLE difference in the pulling angle.. (again try the mathematical simulations..)
Lemain
I apologize, but I'm not very familiar with the imperial units.. but I believe you: 2120 lbs should be 962 kg.. then I have to reformulate my question:
- What will be the effect of a 20 kg Chum on a line with a pull of 962 kg (2 % )??? and if the wind increases to 45 knots or more (not uncommon), then you will reach the ton..
"I'm not sure that mixing stainless with galvanised chain is a good idea, particularly for long-term anchoring, due to potential electrolytic action."
This is not a problem for me, as my anchor is also in stainless steel.. (I have special prices from SPADE.. :0) ) I have been using this stainless steel anchor since 3 years now in long-term anchoring and I can assure you that, if the galvanisation on the first links of the chain is gone, this is more due to the abrasive action of the sand than to the galvanic reaction between zinc and stainless steel..
"You are missing the point, I think. In the right direction, that 20 kg force is enough to pull the anchor free and lift it from the bottom (if it is less than 20kg, anyway). Applied in the right direction, 20kg force is not "peanuts"."
I don't know who is missing the point?? If you can lift your deeply dug in anchor with a vertical force of only 20 kg.. it is time for you to think about changing your anchor.. and sorry, but you are not fair.. we are not talking about lifting vertically an anchor but considering the action of a 20 kg Chum on an anchoring line pulled nearly horizontally, with a force of 962 kg (or more)..
You can consider the point on every angle you want.. Mathematical theories or "Common sense".. you will not be able to demonstrate that this small weight chum will notably change the holding of your anchor..
Now, as I said at the beginning.. If you trust "chums".. please use them.. it will not harm you.. and have a good sleep at anchor.. :0)
On my side, I will launch 10 additional meters of 10 mm chain, (22.5 kg) and this will also give a more horizontal pull.. Much easier and it cost nothing..
Dear Michael and Lemain
I will stop answering your posts as I know that they are people that I will never convince..
Sorry, but we are not playing on the same ground.. You are both using "common beliefs" and what you call "common sense"… I'm using mathematical formulas and I know that you will never trust mathematical demonstrations..
You trust "Kellets" and it helps you to sleep more deeply?? Then, please, use "Kellets" and use two or three of them if you want.. and have a good night.. I don't care, this is not my boat which is attached to your anchoring gear..
On my side, I'm living full time on my boat, she is all my belongings and believe me, I will never trust a kellet..
Michael:
" The Chum/Kellet/ has been around for decades"
Yes, this is absolutely true in UK, but either in the States or in France, very few people are using them..
The "Byblos" anchor has also been used for Centuries, and it is still used in some parts of the world, but it doesn't mean that it is a good anchor (Byblos anchor: Phoenician anchor made of a flat stone with a hole for the rope)
"A chum brings more chain closer to the bottom and the catenary from the chum to the anchor will be more horizontal than it would otherwise have been"
Again I'm sorry but I have to disagree with you.. If you perform mathematical simulations with the Chum at different places on the mooring chain, you will find that the place where the Chum is the most efficient to increase the holding, is as close as possible to the shank of the anchor. In this position, the Chum will keep the shank of the anchor more horizontal, but will not change (or very few increase) the angle of the chain.
As I said before, this is true with light or moderate winds, where nobody care about the holding of the anchor. but with strong winds, when some more holding will be appreciated, the weight of the chum is much too small to make a SENSIBLE difference in the pulling angle.. (again try the mathematical simulations..)
Lemain
I apologize, but I'm not very familiar with the imperial units.. but I believe you: 2120 lbs should be 962 kg.. then I have to reformulate my question:
- What will be the effect of a 20 kg Chum on a line with a pull of 962 kg (2 % )??? and if the wind increases to 45 knots or more (not uncommon), then you will reach the ton..
"I'm not sure that mixing stainless with galvanised chain is a good idea, particularly for long-term anchoring, due to potential electrolytic action."
This is not a problem for me, as my anchor is also in stainless steel.. (I have special prices from SPADE.. :0) ) I have been using this stainless steel anchor since 3 years now in long-term anchoring and I can assure you that, if the galvanisation on the first links of the chain is gone, this is more due to the abrasive action of the sand than to the galvanic reaction between zinc and stainless steel..
"You are missing the point, I think. In the right direction, that 20 kg force is enough to pull the anchor free and lift it from the bottom (if it is less than 20kg, anyway). Applied in the right direction, 20kg force is not "peanuts"."
I don't know who is missing the point?? If you can lift your deeply dug in anchor with a vertical force of only 20 kg.. it is time for you to think about changing your anchor.. and sorry, but you are not fair.. we are not talking about lifting vertically an anchor but considering the action of a 20 kg Chum on an anchoring line pulled nearly horizontally, with a force of 962 kg (or more)..
You can consider the point on every angle you want.. Mathematical theories or "Common sense".. you will not be able to demonstrate that this small weight chum will notably change the holding of your anchor..
Now, as I said at the beginning.. If you trust "chums".. please use them.. it will not harm you.. and have a good sleep at anchor.. :0)
On my side, I will launch 10 additional meters of 10 mm chain, (22.5 kg) and this will also give a more horizontal pull.. Much easier and it cost nothing..
A
Anonymous
Guest
Re: Maths and anchoring
[ QUOTE ]
Dear Michael and Lemain
I will stop answering your posts as I know that they are people that I will never convince..
[/ QUOTE ] Fair enough, lets leave it there. I am an engineer and not in the least bit frightened of maths but when the maths does not reflect what is happening in practice, it is time to change the maths. In any case, most yachtsmen have not studied advanced maths and even those (like myself) who have cannot work out precise calculations for each situation. Indeed, the important variables such as bottom conditons, nature of the sea, relative direction of wind, tide and swell (and the effect on horseing) are far greater than the simple factors such as lenght of scope and weight. Yet for most of us only the scope and the optional use of a chum are controlled variables in any particular situation.
[ QUOTE ]
Dear Michael and Lemain
I will stop answering your posts as I know that they are people that I will never convince..
[/ QUOTE ] Fair enough, lets leave it there. I am an engineer and not in the least bit frightened of maths but when the maths does not reflect what is happening in practice, it is time to change the maths. In any case, most yachtsmen have not studied advanced maths and even those (like myself) who have cannot work out precise calculations for each situation. Indeed, the important variables such as bottom conditons, nature of the sea, relative direction of wind, tide and swell (and the effect on horseing) are far greater than the simple factors such as lenght of scope and weight. Yet for most of us only the scope and the optional use of a chum are controlled variables in any particular situation.
